Open top access refrigerated display case



2 Sheets-Sheet 2 Aug. 24, 1948. M. D. MacMAsTER v OPEN TOP ACCESSREFRIGERATED DISPLAY CASE Filed oct. 2o, 1941 @www Fl g4.

INVENTOR. MALCOLM D. Mac/44145715? BY ZZ Z-WTV ATTORNEY Figi.

Patented Aug. 24, 1948 OPEN TOP ACCESS REFBIGEBATED DISPLAY CASE MalcolmD. MacMaster, Yardley, Pa., asllgnor to y C. V. Hill d: Company, Inc.. acorporation oi' New Jersey Application October 20, 1941, Serial No.415,684

My invention relates to open type refrigerated display cases adapted forthe preservation and display of meats, dairy products and the like.

Open type display cases are of great advantage i in self service storesand elsewhere but they have not generally been used heretofore for thedisplay and preservation of meats and dairy products because of thenecessity of refrigerating such products.

Numerous types of refrigerated vegetable stands which are open at thetop have been developed heretofore. as exemplified by the patent of J.`S.

,Hill, No. 2,207,586, dated July 9, 1940. However.

open type vegetable stands are designed to cause moisture to bedeposited upon the vegetables, whereas the deposition of moisture onmeats and dairy products is objectionable even when such products arewrapped. Furthermore, vegetable stands are generally constructed so thata portion of the cold air from within the display space will spill overthe front or side walls of the case to permit moist warm air to flowinto contact with the vegetables and deposit moisture thereon. Whilethis is desirable in a vegetable stand the continual loss of cold airmaterially reduces the refrigerating efficiency of the construction.

Certain other constructions. such as those used for the display ofsalads and the like in cafeterias,

s claim. (ci. liz-sas) tion of the display space. In this way the airwithin the display space is continuously circulating without drawing insubstantial quantities of warm moist air which might deposit moisture onthe articles being displayed. Moreover, the cooled air is skimmed offthe top of the display space and recirculated so that it does not spillover the front or side walls of the case. By circulating the air withinthe display space the temperature of the air is maintained substantiallyuniform throughout, whereas the refrigerating efficiency of the case ismaintained very high by elimination of losses due to the spilling of thecold air from the case.

. the temperature of the air within the display have been providedheretofore with an open refrigerated well. However, the cold air in suchconstructions 4is not circulated and therefore tends to settle to thebottom of the well with the result that the lower portion of the well ismaintained at a much lower temperature than the upper portion thereof.Such constructions are therefore unsatisfactory for use in thepreservation and display of meats and dairy products.

In accordance with my invention these objections and disadvantages ofconstructions of the prior art are overcome and open type refrigeratedcases are provided wherein objectionable condensation of moisture on theproducts being displayed is avoided while little or no cool air is lostby spilling thereof over the walls of the case. At the same time the airwithin the display space is circulated so as to maintain substantiallyuniform temperatures throughout the display space.

In the preferred embodiments of my invention shown in the figures of thedrawings and hereinafter described, the case is provided with a displayspace which is closed at the bottom and about the sides but is open atthe top and means are provided for withdrawing air from the upperportion of the display space and serve to pass it over refrigeratingmeans back into the lower porsubstantially uniform figures of theaccompanying drawing:

l Fig. 1 is a perspective of a preferred type. of display case embodyingmy-invention.

Fig. 2 is a vertical sectional view ofthe construction illustrated inFig. 1.

Figs. 3 and 4 are diagrammatic sectional views of alternativeconstructions embodying my invention.

In that form of my invention illustrated in Figs. 1 and 2 of thedrawings, the display case is provided with a front wall 2, end walls 4and a rear wall 6. These walls extend upward from the bottom 8 Aof thecase to form a bin having a display and storage space I0 which is closedat the bottom and sides and open at the top. As shown in the drawings, Iprefer to form the upper portion I2 of the front wall 2 with a glasssection so that articles on display within the space' I 0 may be readilyobserved by the customers. lThe lower portion of the front wall as wellasthe I bottom l. the end walls 4 and the rear wall 6 are provided withsuitable thermal insulation to prevent heat loss through the sides andbottom of the case.

Within the display space are located article may be circulated so as topass upward through the openings in the shelf and into contactwith thearticles supported thereon.

The rear wall 6 of the case extends upward a forwardly extendingprojection I6. The front edge of the projection preferably extendsdownwardly at I6 to support illuminating means such as the fluorescentlights 20. Refrigerating means, shown as a refrigerating coil 22, aresupported by the rear wall 6 beneath and adjacent the forwardlyextending projection I6. A baille member 24 is located in front of therefrigerating coil and is spaced from the rear wall 6 so as to providean air circulating duct;k 26 through which air cooled by the coil 22 maypass downward into the lower portion of the display space I0. The lowerportion 28 of the baille 24 is preferably provided with openings 30through. which air may pass from the duct 26 into the display spaceabove the shelf. or article supporting means I4. At the same time aportion of the air flows downwardly through the lower outlet opening 32of the duct 26 into the space 434 beneath the shelf I4 and above thebottom 8 of the case. This air then circulates forward toward the frontof the case and upward through the openings in the shelf so as to bedistributed over the articles being preserved and displayed. A drip pan36 may be located below the outlet opening 32 of the duct 26 to collectany condensate which accumulates on the baille 24 and the lower portion26 thereof so as to conduct such moisture to a drain 36 in the bottom ofthe case.

An important feature of my invention`and one which serves to preventcool air from spilling over the front I2 of the case resides in the warmair bale 4i)l which extends downward from the portion I8 of theprojection I6 at the top 'of the back of the case. The lower edge 42 ofthe warm air baille 40 is located at or below the level of the'upperedge 44 of the front wall of the case. In this way the warm air baillecooperates with the baille 24 to form a 'continua tion 46 of the airduct 26 and to present 'an air inlet 4i!l which is located substantiallyat or below the level of the upper vedge of the front wall of the case.A thermo-syphon is thus edge 44 of'the front wall the operation of thecase is unsuitable for use in the preservation of f meats and dairyproducts because of the deposition of moisture on the articles ondisplay and excessive accumulation of moisture in the form of ice-on thecoils and because of the loss of cold air by spilling thereof over thefront wallof the case. Generally, therefore, I prefer the lower' edge 42of the warm air baille to be located at or somewhat below the level oi'the upper edge of the front of the case. The thermo-syphon then skimsoff the warmest portion of the cool air from the upper portion of thebody of cold air maintained and circulated within the display space andbut little, if any, warm moist air from u coil.

higher than the front wall and is provided with illustrated'in Figs. 1and 2 resides in the loca- A characteristic feature of the constructiontion of the refrigerating coil 22 at an elevation above the level of theupper edge 44 of the front wallvof the display space. With thisconstruction the height of the thermo-syphon and the column of cool airin the air duct 26 is suillciently does mingle with the cool airreturning to the rents of ,sufficient velocity to prevent moist airrefrigerating coil is' cooled thereby so that the coil acts as-aconditioning element which regulates the moisture content of the air andserves to remove excess moisture therefrom. This reg ulation of themoisture content of the air prior to its passage into contact with thearticles beingdisplayed together with the creation of air curfrom cominginto contact with the cooled articles, insures thefpreservation of thearticles in a cooled but dry condition despite the fact that the case isopen to the atmosphere at the top.

In some instances I have found it desirable t0 supplement therefrigerating coil by providing a formed by means of which the airpassed over While the lower edge 42 of the warm air baiev 40 may .bespaced a short distance above the upper edge 44 of the front wall of thecase, I

have found in practice that this distance should not exceed an inch orso for the most eiilcient operation of the case, and when the edge 42 isas much as four inches above the level of the second cooling coil 50located adjacent the bottom of .the display space beneath the shelf I4.However. for most purposes such a supplementary coil is not necessary.

By forming the warm air baille 40 of material having low heatconductivity the deposition of moisture thereon is reduced to a minimum.However, I generally provide a drain gutter 52 at -the lower edge of thewarm-air baille A4I! to conduct any condensate formed to the end of thecase so lthat 'it cannot drip onto the articles being displayed. AItag'molding 54 is positioned adjacent the lower edge of the transparentportion I2 of the front wall of the case for indicating the price ofvarious articles supported on the shelf I4.

While I prefer to employ a construction such as that shown in Figs. l`and 2, in which Ithe -air is circulated by a thermo-syphon action.theair may be positively circulated through the display space, 'asillustrated by the constructions shown in Figs. 3 and 4.

In the construction of Fig. 3 the display case is generally similar tothat shown in Figs. 1 and 2, but a blower or fan 60 is located beneaththe forwardly projecting portion 62 ofthe rear wall 64 of the case so asto draw air positively upward through the portion 66 of the air duct 68land case are all of substantially the same height. The

rear wall 80 of the case is provided with a baille member 82 whichcooperates therewith to form an air duct 84 for circulating the airwithin the display space 8B. The upper end of the air duct communicateswith the display space through the inlet openings 88 located below theupper edge of the rear wall and at or below the level of the upper edgesof the other walls of the case. The lower end of the duc-t 84communicates with the lower portion of the display space through theoutlet opening 90 and a fan or blower 92 is located adjacent the outletopening to draw' air downward through .the air duct 84 and Acirculate ittoward the front of the case beneath the shelf or article supportingmeans 94.

In each of the forms of. my invention illustrated in the drawings theair circulated through the in Fig. 4 diners from that transverselyofsaid section and spaced above said bottom to denne a chamber, an airduct having an upper air inlet opening extending along one portion `ofthe sides adjacent the plane of the lowest portion of the open top ofsaid section and an air outlet communicating with said chamber, meansincluding a motor-driven fan for insuring a positive downward flow ofair through said duct to skim off air from the top of the section anddischarge it downwardly to said chamber, said perforate shelfconstituting not only a supporting means for goods but also means todistribute air display space is drawn from the upper portion of thedisplay space and passed over refrigerating means into the lower portionof the display space, thereby insuring substantially -uniformtemperature conditions throughout the display space. By drawing the airfrom the upper portion of the display space the cool air never builds upto a level above the upper edges of the side walls of the case andtherefore it does not spill over these walls and a high refrigeratingefficiency is maintained.

Moreover, by drawing the air circulated over the coil and over thecooled portions of the case from the body of cool air maintained in thedisplay space, but little, if any, warm moist air from the exterior ofthe case is drawn into the air circuit and the deposition of moisture onthe articles be- -ing displayed and on the cold portions of the case oron the coil, is reduced to a minimum. Furthermore, if moist air from theexterior of the case' ticles on display, so that its temperature isreduced causing its moisture to be deposited on the coil rather than onthe meats or other products inthe display space.

While I have illustrated and described certain preferred embodiments ofmy invention, it will be readily understood that the form, design', andconstruction of open type display cases embodying my invention may bevaried considerably. Thus, for example, construction generally similarto that shown and described in the copending application of Floyd C.Lowell, Serial No. 378,503, led February 12, 1941, now Patent No.2,290,647, granted July 21, 1942, maybe employed without using the doorswhich close the top of the -display space.Vv Therefore, it should beunderstood that the embodiments of my invention shown in the drawingsand herein described are intended to be illustrative of my invention andare not intended to limit the scope thereof.

I claim:

1. An open self service refrigerated display case having means formaintaining a continuous recirculation of cooled air within the continesof an open topped section thereof with minimum loss of such air oraddition of outer air, said case including an element forming the bottomof said open topped section, wall structure extending substantiallyvertically therefrom to denne the sides of said section. a perforateshelf extending from said .chamber upwardly throughout the crosssectional area of said section above said shelf, and means for coolingthe air within said section.

2. An open self service refrigerated display case having means formaintaining a continuous recirculation of cooled air within the confinesof an open topped section thereof with minimum loss of such air oraddition of outer air, said case including an element forming the bottomof said open topped section, wall structure extending substantiallyvertically therefrom to define the sides of said section, a perforateshelf extending transversely of said section and spaced above said.bottom to define a chamber, an air duct having an upper-air inletopening extending along one portion of the sides adjacent the plane ofthe lowest portion of the open top of said section and an air outletcommunicating with said chamber, means including refrigeratng coilsWithin said duct and a motor-driven fan for insuring a positive downwardflow of air through said duct to skim oi air from the top of the sectionand disincluding an element forming the lbottom of said open toppedsection, wall structure extending substantially vertically therefrom todefine the sides of said section, a perforate shelf extendingtransversely of said section and spaced above said bottom to define achamber, an air duct having an upper air inlet opening extending alongone portion of the sides adjacent the plane of the lowest portion of theopen top of said section and an air outlet communicating with saidchamber,

' means including refrigerating coils and a motordriven fan for insuringa, positive downward ilow of air through said duct to skim off air fromthe top of the section and discharge it downwardly to said chamber, saidperforate shelf constituting not onlya supporting means for goods butalso means to distribute air from said chamber upwardly throughout thecross sectional area of said section above said shelf and inwardlydirected baiiles adjacent said open top opposite said upper air inlet todirect air across said open top towards said inlet.

MALCOLM D. MACMASTE'R.

(References on following page) 7 nnmnuczs cum "The following referencesare o! record ln the 111e of this patent:

' UNITED STATES PATENTS Number Number Numa Data Murphy Dec. 29,l 1936Balen Jan. 8. 1937 Gardner June 8, 1937 Gray June 14, 1938 Smith Nov.14, 1939 Blz-eley Oct.v 29, 1940 Wolf Nov. 19, 1940 Starr Sept. 30, 1941Nordskog Feb. 3, 1942 Caulk et al Aug. 14, 1945

